The present invention relates to an inking apparatus for a printing press, wherein an ink is applied to a plate surface.
A conventional printing press inking apparatus for applying an ink to a surface of a plate attached to a plate cylinder comprises an ink fountain for storing an ink and a roller group for transferring an ink flowed out from the ink fountain and for uniformly distributing the ink in all directions. The ink transferred to vibrating rollers located near the end of the roller group is applied to the plate surface through form rollers. Each vibrating roller in the inking apparatus is rotated and axially vibrated by a motor. Each form roller is supported by shaft end portions of the corresponding vibrating roller through arms and is in contact with the vibrating roller. The form roller can be brought into contact with or separated from the plate surface by swinging the arms. The form roller transfers the ink to the plate surface while being brought into contact with the vibrating roller and the plate surface. The form roller is rotated by gear coupling arranged with the vibrating roller and is axially vibrated by a grooved cam arranged at the end portion thereof.
Japanese Patent Laid-Open (Kokai) No. 60-101049 describes a construction wherein a form roller is not positively driven but is rotated and axially vibrated by friction between the vibrating and form rollers.
Vibrations of the form roller aim at distributing local picture remaining portions (a so-called ghost) of the plate surface. When a vibration stroke of the form roller is excessively long, durability of an inking mechanism and printing on the plate surface are degraded. The vibration stroke is preferably minimized. Therefore, the vibration stroke is preferably adjusted to a given ghost level.
In the form rollers in the conventional inking apparatuses described above, the mechanism with the grooved cam and the mechanism utilizing friction between the vibrating and form rollers cannot adjust the vibration strokes. As a result, the durability of the mechanisms cannot be improved. In particular, the mechanism with the grooved cam cannot stop axial vibration. In order to improve the durability of the mechanism, vibrating and nonvibrating rollers are prepared and selectively used for types of printed matters. For this reason, a long preparation time including a nip adjustment time is required, and therefore productivity is degraded and a large amount of paper is wasted.